Math.atanh() - JavaScript 编辑

Math.atanh() 函数返回一个数值反双曲正切值, 即：

$$\forall x \in \left( -1, 1 \right), \mathtt{\operatorname{Math.atanh}(x)} = \operatorname{arctanh}(x) = \text{ the unique } \; y \; \text{such that} \; \tanh(y) = x$$

语法

Math.atanh(x)

参数

x

一个数值

描述

由于 atanh() 是 Math 的静态方法,所以应该像这样使用：Math.atanh()，而不是作为你创建的 Math 实例的方法（Math 不是一个构造函数）。 

示例

使用 Math.atanh()

Math.atanh(-2);  // NaN
Math.atanh(-1);  // -Infinity
Math.atanh(0);   // 0
Math.atanh(0.5); // 0.5493061443340548
Math.atanh(1);   // Infinity
Math.atanh(2);   // NaN

对于大于1或是小于－1的值，函数返回 NaN 。

Polyfill

For \left|x\right| < 1, we have \operatorname {artanh} (x) = \frac{1}{2}\ln \left( \frac{1 + x}{1 - x} \right) so this can be emulated by the following function:

Math.atanh = Math.atanh || function(x) {
  return Math.log((1+x)/(1-x)) / 2;
};

规范

Specification	Status	Comment
ECMAScript 2015 (6th Edition, ECMA-262) Math.atanh	Standard	Initial definition.
ECMAScript Latest Draft (ECMA-262) Math.atanh	Draft

浏览器兼容性

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

• Desktop
• Mobile

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	38	25 (25)	未实现	25	7.1

Feature	Android	Chrome for Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	未实现	未实现	25.0 (25)	未实现	未实现	8

相关链接

• Math.acosh()
• Math.asinh()
• Math.cosh()
• Math.sinh()
• Math.tanh()